Form Interaction

/**
 * HTML form element with submission and field management
 */
public class HtmlForm extends HtmlElement {
    /** Submit form using default submit button */
    public <P extends Page> P submit() throws IOException;
    
    /** Submit form using specific submit element */
    public <P extends Page> P submit(SubmittableElement submitElement) throws IOException;
    
    /** Reset form to default values */
    public void reset();
    
    /** Get form method (GET/POST) */
    public String getMethodAttribute();
    
    /** Get form action URL */
    public String getActionAttribute();
    
    /** Get form encoding type */
    public String getEnctypeAttribute();
    
    /** Get form target */
    public String getTargetAttribute();
    
    /** Get input element by name */
    public HtmlElement getInputByName(String name);
    
    /** Get all input elements by name */
    public List<HtmlElement> getInputsByName(String name);
    
    /** Get text input by value */
    public HtmlTextInput getInputByValue(String value);
    
    /** Get elements by tag name within form */
    public List<HtmlElement> getHtmlElementsByTagName(String tagName);
    
    /** Get select element by name */
    public HtmlSelect getSelectByName(String name);
    
    /** Get all select elements by name */
    public List<HtmlSelect> getSelectsByName(String name);
    
    /** Get textarea by name */
    public HtmlTextArea getTextAreaByName(String name);
    
    /** Get button by name */
    public HtmlButton getButtonByName(String name);
    
    /** Check if form accepts file uploads */
    public boolean isMultiPartForm();
    
    /** Get form's character set */
    public String getAcceptCharsetAttribute();
    
    /** Check if form validation is disabled */
    public boolean isNoValidate();
}

import com.gargoylesoftware.htmlunit.html.*;

try (WebClient webClient = new WebClient()) {
    HtmlPage page = webClient.getPage("https://example.com/login");
    
    // Find and fill login form
    HtmlForm loginForm = page.getFormByName("loginForm");
    
    HtmlTextInput usernameField = loginForm.getInputByName("username");
    usernameField.setValueAttribute("john.doe");
    
    HtmlPasswordInput passwordField = (HtmlPasswordInput) loginForm.getInputByName("password");
    passwordField.setValueAttribute("secretpassword");
    
    HtmlCheckBoxInput rememberMe = (HtmlCheckBoxInput) loginForm.getInputByName("remember");
    rememberMe.setChecked(true);
    
    // Submit form
    HtmlSubmitInput submitButton = (HtmlSubmitInput) loginForm.getInputByName("submit");
    HtmlPage resultPage = submitButton.click();
    
    // Or submit directly
    HtmlPage resultPage2 = loginForm.submit();
}

/**
 * Base class for HTML input elements
 */
public abstract class HtmlInput extends HtmlElement implements SubmittableElement, DisabledElement {
    /** Get input type attribute */
    public String getTypeAttribute();
    
    /** Get input value */
    public String getValueAttribute();
    
    /** Set input value */
    public void setValueAttribute(String value);
    
    /** Get input name */
    public String getNameAttribute();
    
    /** Get default value */
    public String getDefaultValue();
    
    /** Set default value */
    public void setDefaultValue(String defaultValue);
    
    /** Check if input is disabled */
    public boolean isDisabled();
    
    /** Set disabled state */
    public void setDisabled(boolean disabled);
    
    /** Check if input is read-only */
    public boolean isReadOnly();
    
    /** Set read-only state */
    public void setReadOnly(boolean readOnly);
    
    /** Check if input is required */
    public boolean isRequired();
    
    /** Get input size attribute */
    public String getSizeAttribute();
    
    /** Get maxlength attribute */
    public String getMaxLengthAttribute();
    
    /** Get placeholder text */
    public String getPlaceholderAttribute();
    
    /** Check if input has focus */
    public boolean hasFocus();
    
    /** Select all text in input */
    public void select();
    
    /** Get form containing this input (if any) */
    public HtmlForm getEnclosingForm();
    
    /** Check if input value is valid */
    public boolean isValid();
    
    /** Get validation message */
    public String getValidationMessage();
    
    /** Check validity and show validation message */
    public boolean checkValidity();
    
    /** Set custom validation message */
    public void setCustomValidity(String message);
}

/**
 * Single-line text input (<input type="text">)
 */
public class HtmlTextInput extends HtmlInput {
    /** Type text into field (fires events) */
    public void type(String text) throws IOException;
    
    /** Append text to existing value */
    public void appendText(String text) throws IOException;
    
    /** Clear the input field */
    public void clear();
    
    /** Get text selection start position */
    public int getSelectionStart();
    
    /** Get text selection end position */
    public int getSelectionEnd();
    
    /** Set text selection range */
    public void setSelectionRange(int start, int end);
}

/**
 * Password input (<input type="password">)
 */
public class HtmlPasswordInput extends HtmlInput {
    /** Type password text (fires events) */
    public void type(String text) throws IOException;
    
    /** Clear password field */
    public void clear();
}

/**
 * Hidden input (<input type="hidden">)
 */
public class HtmlHiddenInput extends HtmlInput {
    // Hidden inputs have same base functionality as HtmlInput
}

/**
 * Email input (<input type="email">)
 */
public class HtmlEmailInput extends HtmlInput {
    /** Type email text (fires events) */
    public void type(String text) throws IOException;
    
    /** Get list attribute for datalist */
    public String getListAttribute();
}

/**
 * Number input (<input type="number">)
 */
public class HtmlNumberInput extends HtmlInput {
    /** Get min value */
    public String getMinAttribute();
    
    /** Get max value */
    public String getMaxAttribute();
    
    /** Get step value */
    public String getStepAttribute();
    
    /** Step up by specified amount */
    public void stepUp(int n);
    
    /** Step down by specified amount */
    public void stepDown(int n);
}

/**
 * URL input (<input type="url">)
 */
public class HtmlUrlInput extends HtmlInput {
    /** Type URL text (fires events) */
    public void type(String text) throws IOException;
}

/**
 * Search input (<input type="search">)
 */
public class HtmlSearchInput extends HtmlInput {
    /** Type search text (fires events) */
    public void type(String text) throws IOException;
}

/**
 * Telephone input (<input type="tel">)
 */
public class HtmlTelephoneInput extends HtmlInput {
    /** Type telephone text (fires events) */
    public void type(String text) throws IOException;
}

/**
 * Submit button (<input type="submit">)
 */
public class HtmlSubmitInput extends HtmlInput {
    /** Click to submit form */
    public <P extends Page> P click() throws IOException;
    
    /** Get form value sent when this button submits */
    public String getValueAttribute();
}

/**
 * Generic button (<input type="button">)
 */
public class HtmlButtonInput extends HtmlInput {
    /** Click button (fires events) */
    public <P extends Page> P click() throws IOException;
}

/**
 * Reset button (<input type="reset">)
 */
public class HtmlResetInput extends HtmlInput {
    /** Click to reset form */
    public <P extends Page> P click() throws IOException;
}

/**
 * Image button (<input type="image">)
 */
public class HtmlImageInput extends HtmlInput {
    /** Click image button */
    public <P extends Page> P click() throws IOException;
    
    /** Click at specific coordinates */
    public <P extends Page> P click(int x, int y) throws IOException;
    
    /** Get image source URL */
    public String getSrcAttribute();
    
    /** Get image alt text */
    public String getAltAttribute();
}

/**
 * Button element (<button>)
 */
public class HtmlButton extends HtmlElement implements SubmittableElement, DisabledElement {
    /** Click button */
    public <P extends Page> P click() throws IOException;
    
    /** Get button type (submit/button/reset) */
    public String getTypeAttribute();
    
    /** Get button name */
    public String getNameAttribute();
    
    /** Get button value */
    public String getValueAttribute();
    
    /** Check if disabled */
    public boolean isDisabled();
    
    /** Set disabled state */
    public void setDisabled(boolean disabled);
    
    /** Get form containing button */
    public HtmlForm getEnclosingForm();
}

/**
 * Checkbox input (<input type="checkbox">)
 */
public class HtmlCheckBoxInput extends HtmlInput {
    /** Check if checkbox is checked */
    public boolean isChecked();
    
    /** Set checked state */
    public void setChecked(boolean checked);
    
    /** Get checkbox value when checked */
    public String getValueAttribute();
    
    /** Check if checkbox is indeterminate */
    public boolean isIndeterminate();
    
    /** Set indeterminate state */
    public void setIndeterminate(boolean indeterminate);
    
    /** Click to toggle checked state */
    public <P extends Page> P click() throws IOException;
}

/**
 * Radio button (<input type="radio">)
 */
public class HtmlRadioButtonInput extends HtmlInput {
    /** Check if radio button is selected */
    public boolean isChecked();
    
    /** Set selected state (unselects others in group) */
    public void setChecked(boolean checked);
    
    /** Get radio button value */
    public String getValueAttribute();
    
    /** Click to select this radio button */
    public <P extends Page> P click() throws IOException;
    
    /** Get other radio buttons in same group */
    public List<HtmlRadioButtonInput> getRadioGroup();
}

/**
 * File upload input (<input type="file">)
 */
public class HtmlFileInput extends HtmlInput {
    /** Set files to upload */
    public void setFiles(File... files);
    
    /** Set file data directly */
    public void setData(byte[] data);
    
    /** Set file with specific filename and content type */
    public void setContentType(String contentType);
    
    /** Get uploaded files */
    public File[] getFiles();
    
    /** Check if multiple files allowed */
    public boolean isMultiple();
    
    /** Get accepted file types */
    public String getAcceptAttribute();
    
    /** Clear selected files */
    public void clearFiles();
}

// File upload
HtmlFileInput fileInput = (HtmlFileInput) form.getInputByName("attachment");
File uploadFile = new File("/path/to/document.pdf");
fileInput.setFiles(uploadFile);

// Multiple file upload
File[] files = {
    new File("/path/file1.jpg"),
    new File("/path/file2.png")
};
fileInput.setFiles(files);

// Direct data upload
byte[] fileData = "file content".getBytes();
fileInput.setData(fileData);
fileInput.setContentType("text/plain");

/**
 * Select dropdown (<select>)
 */
public class HtmlSelect extends HtmlElement implements SubmittableElement, DisabledElement {
    /** Get all option elements */
    public List<HtmlOption> getOptions();
    
    /** Get currently selected options */
    public List<HtmlOption> getSelectedOptions();
    
    /** Get option by value attribute */
    public HtmlOption getOptionByValue(String value);
    
    /** Get option by display text */
    public HtmlOption getOptionByText(String text);
    
    /** Get option at index */
    public HtmlOption getOption(int index);
    
    /** Set option selected by value */
    public void setSelectedAttribute(String value, boolean selected);
    
    /** Set option selected by index */
    public void setSelectedIndex(int index);
    
    /** Check if multiple selection is enabled */
    public boolean isMultipleSelectEnabled();
    
    /** Get select name */
    public String getNameAttribute();
    
    /** Get select size (visible options) */
    public String getSizeAttribute();
    
    /** Check if disabled */
    public boolean isDisabled();
    
    /** Set disabled state */
    public void setDisabled(boolean disabled);
    
    /** Check if required */
    public boolean isRequired();
    
    /** Get form containing select */
    public HtmlForm getEnclosingForm();
    
    /** Clear all selections */
    public void clearSelection();
}

/**
 * Option element (<option>)
 */
public class HtmlOption extends HtmlElement {
    /** Check if option is selected */
    public boolean isSelected();
    
    /** Set selected state */
    public void setSelected(boolean selected);
    
    /** Get option value */
    public String getValueAttribute();
    
    /** Get option display text */
    public String getText();
    
    /** Check if option is disabled */
    public boolean isDisabled();
    
    /** Set disabled state */
    public void setDisabled(boolean disabled);
    
    /** Get option index in select */
    public int getIndex();
    
    /** Click to select option */
    public <P extends Page> P click() throws IOException;
}

/**
 * Option group (<optgroup>)
 */
public class HtmlOptionGroup extends HtmlElement {
    /** Get group label */
    public String getLabel();
    
    /** Check if group is disabled */
    public boolean isDisabled();
    
    /** Get options in this group */
    public List<HtmlOption> getOptions();
}

// Select dropdown manipulation
HtmlSelect countrySelect = form.getSelectByName("country");

// Select by value
countrySelect.setSelectedAttribute("US", true);

// Select by text
HtmlOption canadaOption = countrySelect.getOptionByText("Canada");
canadaOption.setSelected(true);

// Multiple selection
HtmlSelect skillsSelect = form.getSelectByName("skills");
if (skillsSelect.isMultipleSelectEnabled()) {
    skillsSelect.setSelectedAttribute("java", true);
    skillsSelect.setSelectedAttribute("python", true);
    skillsSelect.setSelectedAttribute("javascript", true);
}

// Get selected values
List<HtmlOption> selected = countrySelect.getSelectedOptions();
for (HtmlOption option : selected) {
    System.out.println("Selected: " + option.getValueAttribute());
}

/**
 * Multi-line text area (<textarea>)
 */
public class HtmlTextArea extends HtmlElement implements SubmittableElement, DisabledElement {
    /** Get textarea text content */
    public String getText();
    
    /** Set textarea text content */
    public void setText(String text);
    
    /** Get textarea name */
    public String getNameAttribute();
    
    /** Get number of rows */
    public int getRows();
    
    /** Get number of columns */
    public int getCols();
    
    /** Check if disabled */
    public boolean isDisabled();
    
    /** Set disabled state */
    public void setDisabled(boolean disabled);
    
    /** Check if read-only */
    public boolean isReadOnly();
    
    /** Set read-only state */
    public void setReadOnly(boolean readOnly);
    
    /** Check if required */
    public boolean isRequired();
    
    /** Get maximum length */
    public String getMaxLengthAttribute();
    
    /** Get placeholder text */
    public String getPlaceholderAttribute();
    
    /** Type text (fires events) */
    public void type(String text) throws IOException;
    
    /** Select all text */
    public void select();
    
    /** Get form containing textarea */
    public HtmlForm getEnclosingForm();
    
    /** Get text selection start */
    public int getSelectionStart();
    
    /** Get text selection end */
    public int getSelectionEnd();
    
    /** Set selection range */
    public void setSelectionRange(int start, int end);
}

/**
 * Date input (<input type="date">)
 */
public class HtmlDateInput extends HtmlInput {
    /** Get min date */
    public String getMinAttribute();
    
    /** Get max date */
    public String getMaxAttribute();
    
    /** Get step attribute */
    public String getStepAttribute();
    
    /** Step up by specified amount */
    public void stepUp(int n);
    
    /** Step down by specified amount */
    public void stepDown(int n);
}

/**
 * Time input (<input type="time">)
 */
public class HtmlTimeInput extends HtmlInput {
    /** Get min time */
    public String getMinAttribute();
    
    /** Get max time */
    public String getMaxAttribute();
    
    /** Get step attribute */
    public String getStepAttribute();
    
    /** Step up by specified amount */
    public void stepUp(int n);
    
    /** Step down by specified amount */
    public void stepDown(int n);
}

/**
 * DateTime-local input (<input type="datetime-local">)
 */
public class HtmlDateTimeLocalInput extends HtmlInput {
    /** Get min datetime */
    public String getMinAttribute();
    
    /** Get max datetime */
    public String getMaxAttribute();
    
    /** Get step attribute */
    public String getStepAttribute();
    
    /** Step up by specified amount */
    public void stepUp(int n);
    
    /** Step down by specified amount */
    public void stepDown(int n);
}

/**
 * Interface for elements that can be submitted with forms
 */
public interface SubmittableElement {
    /** Get element name for form submission */
    String getName();
    
    /** Get element value for form submission */
    String getValue();
    
    /** Set default value */
    void setDefaultValue(String defaultValue);
    
    /** Reset to default value */
    void reset();
}

/**
 * Interface for elements that can be disabled
 */
public interface DisabledElement {
    /** Check if element is disabled */
    boolean isDisabled();
    
    /** Set disabled state */
    void setDisabled(boolean disabled);
}

/**
 * Interface for form validation
 */
public interface ValidatableElement {
    /** Check if element value is valid */
    boolean isValid();
    
    /** Get validation message */
    String getValidationMessage();
    
    /** Check validity and show message */
    boolean checkValidity();
    
    /** Set custom validation message */
    void setCustomValidity(String message);
}

/**
 * Form encoding type constants
 */
public class FormEncodingType {
    /** URL encoded form data (default) */
    public static final FormEncodingType URL_ENCODED = new FormEncodingType("application/x-www-form-urlencoded");
    
    /** Multipart form data (for file uploads) */
    public static final FormEncodingType MULTIPART = new FormEncodingType("multipart/form-data");
    
    /** Plain text encoding */
    public static final FormEncodingType TEXT_PLAIN = new FormEncodingType("text/plain");
    
    /** Get encoding type name */
    public String getName();
}